Catalytic reforming, or hydroforming, is a well established industrial process employed by the petroleum industry for improving the octane quality of naphthas or straight run gasolines. In reforming, a multi-functional catalyst is employed which typically contains a metal hydrogenation-dehydrogenation (hydrogen transfer) component or components, substantially atomically dispersed upon the surface of a porous inorganic oxide support, notably alumina.
In recent years, platinum has been widely commercially used as the metallic hydrogen transfer component of reforming catalysts, and platinum-on-alumina catalysts have been commercially employed in refineries. Also, additional metallic components, such as rhenium, iridium, ruthenium, tin, palladium, germanium and the like, have been added to platinum as promoters to further improve the activity, selectivity, or both, of the basic platinum catalyst.
In a conventional reforming process, a series of reactors constitute the heart of the reforming unit. Each reforming reactor is generally provided with a fixed bed or beds of the catalyst which receive upflow or downflow feed. Each reactor is provided with a heater because the reactions which take place therein are endothermic. In a conventional reforming process, a naphtha feed with hydrogen or hydrogen recycle gas is passed through a preheat furnace, then downward through a reactor, and then in sequence through subsequent interstage heaters and reactors of the series. The product of the last reactor is separated into a liquid fraction and a vaporous effluent. The vaporous effluent, a gas rich in hydrogen, is used as hydrogen recycle gas in the reforming process.
During operation, the activity of the reforming catalyst gradually declines due to the build-up of coke, and the temperature of the process is gradually raised to compensate for the activity loss caused by the coke deposits. Eventually, economics dictate the necessity of regenerating the catalyst.
The initial phase of catalyst regeneration is accomplished by burning the coke off the catalyst under controlled conditions. Catalyst regeneration is then completed through a sequence of activation steps wherein the agglomerated metal hydrogenation-dehydrogenation components are atomically redispersed. Such activation generally is achieved by treating the catalyst with hydrogen to effect reduction of the platinum oxide, and such other oxides as may be present in the catalyst system, followed by a chloride treatment of the reduced catalyst system prior to placing it back into use.
In addition to the activation process required when working with a catalyst which has been subjected to regeneration by burning off coke from the catalyst, there is generally carried out an activation treatment of the initially charged catalyst to the reactor prior to the introduction of hydrocarbon feed to the system.
In both the activation of fresh catalyst as well as the activation of a regenerated catalyst there have been numerous efforts to achieve a catalyst system whereby the catalyst will have increased activity, provide a product having increased octane values and avoid the undesirable cracking of product.
It is an object of the present invention to provide a process for the regeneration and activation of a platinum reforming catalyst.
Another object of the invention is to provide an improved system for the activation of a platinum reforming catalyst whereby the catalyst activity is increased.
A still further object of this invention is to provide an improved process for the activation of a platinum reforming catalyst which, when the activated catalyst is used in the reforming of a reformer feed, the cracking of such feed to undesired byproducts is reduced.
Yet another object of this invention is to provide a process for the activation of a platinum reforming catalyst which, when the activated catalyst is used in the reforming of a reformer feed, the cracking of such feed is decreased while the octane number of the reformer product is increased.
Other aspects, objects and the several advantages of the invention will be apparent from the following specification and appended claims.